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<TITLE>HyperText Design Issues: Link types</TITLE>
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<H1>Link Types</H1>See <A
NAME=3 HREF="Topology.html#4">discussion of whether links should
be typed</A> .<P>
Descriptive (normal) link types are
mainly for the benefit of users and
tracing, and graphics representation
algorithms. Some link types for example
express relationships between the
things described by two nodes.<P>
A Is part of B  / B includes A<P>
A Made B / B is made by A<P>
A Uses B  / B is used by A<P>
A refers to B / B is referred to
by A
<H2>Magic link types</H2>These have a significance known to
the system, and may be treated in
special ways.  Many of these relate
whole nodes, rather than particular
anchors within them.  (See also <A
NAME=4 HREF="Topology.html#12">multiended
links</A> and predicate logic) Suggestions:
<H2>UseIndex</H3>The destination is the related index
for a search by a user reading this
document who asks for an index search
function.<P>
A document may have any number of
index links, causing several indexes
top be searched in a client-defined
manner.
<H2>UseGlossary</H3>The destination of the link is an
index which should be used to resiolve
glossary queries in the document.
(Typically, a double-clik on a word
which is not within an anchor).<P>
A document may have any number of
glossary links.
<H2>Annotation</H3>The information in the destination
node is additional to that in the
source node, and may be viewed at
the same time. It may be filtered
out (as a function of author?).<P>
Annotation is used by one person
to write the equivalent of "margin
notes" or other criticism on another's
document, for example.<P>
<A
NAME=2 HREF="TracingLinks.html">Tracing</A> may ignore annotations when
generating trees or sequences.
<H2>Embedded information</H3>If this link is followed, the node
at the end of it is embedded into
the display of the source node. This
is supported by Guide, but not many
other systems.  It is used, in effect,
by those systems (VAX/notes under
Decwindows, Microsoft Word) which
allow "Outlining" -- expanding a
tree bit by bit.<P>
The browser has a more difficult
job to do if this is supported.
<H2>person described by node A is author
of node B</H2>This information can be used for
protection, and informing authors
of interest, for sending mail to
authors, etc.
<H2>person described by node A is interested
in node B</H2>This information can be used for
informing readers of changes.
<H2><A
NAME=1>Node A is in fact a previous version
of node B</A></H2>
<H2>Node A is in fact a set of differences
between B and its previous</H3>version. This information will probably
not be stored as nodes, but be generated
from regular diff files. or some
other delta method.</BODY>
